In order to treat a disorder known as pulpitis, the diseased pulpa is first removed mechanically from the root canal. Next, the root canal is cleaned, drilled out, and filled with an elastic-plastic element or with a different filling material. Finally, the root canal is sealed. Prior art illustrative of this process includes: Friedman et al. in J. Dent. Res., 54 (1975) 921-925; Briseno in Philipp J., 2, 90, 65-73; and U.S. Pat. No. 4,632,977. Suitable root canal filling materials, as described by Briseno, include inter alia semi-rigid cements based on synthetic resin, zinc oxide eugenol, calcium hydroxide or glass ionomer. U.S. Pat. No. 4,632,977 proposes filling materials based on trans-polyisoprene (for example, filling materials based on gutta-percha or balata). Gutta-percha points are commercially available in standard compositions that comprise: 20% by weight of gutta-percha matrix; from 60 to 75% by weight of zinc oxide filler; from 1 to 17% by weight of heavy metal sulphates that serve as X-ray contrast agents; and from 3 to 4% by weight of various waxes and resins that serve as softener. The aforementioned filling material is inert in the root canal and accordingly does not react with body tissue.
When a root canal has been filled with a known inert filling material, an inflammatory process may slowly develop after the filling operation (for example, as a result of germs remaining in the canal). The inflammation requires renewed treatment which often results in the complete loss of the tooth.
In response to this problem, compositions comprising antibiotics or calcium hydroxide have been used. Unfortunately, antibiotics have a large number of side-effects. For example, the use of antibiotics can result in the development of resistant bacterial strains. Therefore, the use of antibiotics is increasingly being rejected, especially for children.
The alternative use of calcium hydroxide is, in many cases, successful. However, it has recently been established that a number of bacteria, including Streptococcus micros and Enterococcus faecalis, are resistant to calcium hydroxide even at a pH value of 11. Therefore, these bacteria cannot be completely killed with calcium hydroxide.
U.S. Pat. Nos. 1,754,577 and 5,648,403 describe sealing root canals with a carrier comprising iodine-containing compounds. However, it has been recognized that a continuous release of iodine into the human body can result in deleterious side-effects and moreover that iodine compounds have an unattractive odor.
Iodine-containing and chlorhexidine-containing solutions for rinsing the oral cavity especially before, during and after surgical interventions, have also been disclosed. Illustrative examples of such disclosures include U.S. Pat. No. 4,738,840, U.S. Pat. No. 3,932,607, and the following foreign references: EP 94 102 340.0, RU 200 88 42, SU 165 0 138, and JP 622 65 225. In addition, the following references describe compositions comprising antibacterial compounds in a biodegradable or soluble carrier: EP 90 302 837.1 and WO 89/10 736.
The present invention solves many of the problems in the prior art by providing an anti-inflammatory composition for filling root canals in humans or animals that can be prepared and processed readily and simply. The present invention also provides a method of preparing such a composition.